JP5178280B2 - Vacuum insulation structure - Google Patents

Description

The present invention is a heat-insulating material relates vacuum insulation structure comprising hermetically packaged in a multi-layer film, and more particularly, gas barrier properties, particularly excellent water vapor barrier property under a high humidity, further excellent in thermal insulation performance The present invention relates to a vacuum heat insulation structure using a multilayer film.

  Conventionally, insulation materials using polyurethane foam have been used as insulation materials for refrigerators, electric pots, etc., or insulation panels for residential insulation walls, but in recent years, as an excellent alternative to this, glass wool, oxidation Vacuum heat insulating structures in which a heat insulating material such as silicon or foamed resin is used as a core material, this is sealed with a gas barrier laminate film, and the inside is vacuumed have begun to be used.

  In such a vacuum heat insulating structure, a multilayer structure using a vinyl alcohol film or an aluminum foil is used as a gas barrier laminate film, and as the vinyl alcohol film, a plastic film made of a polyvinyl alcohol resin, A multilayer structure using a film made of an ethylene-vinyl alcohol copolymer is used.

  For example, the vacuum heat insulating structure composed of a multilayer film containing an ethylene-vinyl alcohol copolymer resin film includes a core material and an outer bag envelope material that encloses the core material, and the outer bag is a vapor deposition Laminate films having a layer, or a laminate film having a vapor deposition layer, and a laminate film having a metal foil are formed into a bag shape by heat welding, and the laminate film having the vapor deposition layer is a heat weld layer, A gas barrier layer and an outermost layer, wherein the gas barrier layer is obtained by performing aluminum vapor deposition on one side of a plastic film made of an ethylene-vinyl alcohol copolymer resin, and the surface on which the aluminum vapor deposition is performed is a heat welding layer. A vacuum insulator provided on the side has been proposed (see, for example, Patent Document 1).

  Moreover, in the vacuum heat insulation structure using the conventional vinyl alcohol-type film, vapor deposition PET is laminated | stacked on the outer side of a gas barrier layer, and also nylon film may be laminated | stacked in the outermost layer in order to ensure further gas barrier property. Yes (see, for example, Patent Document 2).

JP-A-10-122477 WO 2007/020978

  However, a laminate film having a metal foil is poor in resistance to expansion and contraction due to the use of metal, and when expansion or bending is applied to an exterior bag of a vacuum heat insulating structure composed of such a film, the film cracks in that portion. Further, there is a drawback that the film has a pinhole and the gas barrier property of the film is remarkably lowered, and the heat insulation performance as a vacuum heat insulation structure is lowered. On the other hand, the layer structure having the nylon film as the outermost layer has a drawback that the gas barrier property under high humidity is insufficient. Such a vacuum heat insulating structure is used for a heat insulating panel for a refrigerator or a heat insulating wall for a house, and is used in an environment that is susceptible to the influence of outside air. There has been a demand for a vacuum heat insulating structure having excellent gas barrier properties.

Therefore, it in such a background under the present invention, gas barrier properties, particularly excellent water vapor barrier property under a high humidity, further to provide a vacuum insulation structure using the multilayer fill beam with excellent thermal insulation performance It is intended.

However, as a result of intensive research in view of such circumstances, the present inventor used a vapor deposition substrate film having at least two aluminum vapor deposition layers deposited in multiple stages in hermetically packaging the heat insulating material. It was found that by combining with a gas barrier film, a vacuum heat insulating structure excellent in gas barrier property, particularly water vapor barrier property under high humidity, and also in heat insulating performance was obtained, and the present invention was completed.

That is, the gist of the present invention, have a layer structure of the vapor deposition substrate film having at least two layers of aluminum deposited layer formed by a multistage evaporation (A) / gas barrier film (B), and a gas barrier film (B) provides a vacuum heat insulating structure in which a heat insulating material is hermetically packaged by a multilayer film which is a biaxially stretched polyvinyl alcohol film .

  In short, the vacuum heat insulating structure of the present invention uses, as a multilayer film for hermetically wrapping a heat insulating material, a vapor deposited substrate film that has conventionally been subjected to only one vapor deposition treatment on the substrate film. As usual, it is characterized by using a vapor deposition substrate film which has been vapor-deposited in multiple stages.

Vacuum insulating structure of the present invention, the thermally insulating material Upon sealing packaged using the multilayer film, by using a vapor deposition substrate film which is formed by a multistage evaporation (A), gas barrier properties, particularly high humidity It shows excellent effects in water vapor barrier properties and heat insulation performance in the case of, and even when wrinkles are generated in the multilayer film when the heat insulating material is sealed under reduced pressure with the multilayer film, it is added to these wrinkle portions. High resistance to the occurrence of cracks or pinholes due to local stress. As a result, the vacuum can be maintained with high reliability even when used for a long period of time, and the heat insulation performance does not deteriorate. Is.

  The present invention is described in detail below.

The multilayer film in this invention contains the vapor deposition base film (A) and gas-barrier film (B) which have the at least 2 or more aluminum vapor deposition layer formed by multistage vapor deposition.

  As this vapor deposition base film (A), the base film which has a vapor deposition layer formed by performing a multistep vapor deposition process on a base film can be used.

Examples of the base film in the present invention include a polyester film, a polyolefin film, a polyamide film, a polyether film, and a polyurethane film. Among them, a polyester film and a polyolefin film are used. Are preferable from the viewpoints of processability, durability and economy, and polyethylene terephthalate (PET) film, polybutylene terephthalate (PBT) film, and polypropylene (OPP) film are particularly preferable, and polyethylene terephthalate (PE) is particularly preferable.
T) Film is preferred.
Further, it is preferable to use a film that has been subjected to a stretching treatment, and it is particularly preferable to use a biaxially stretched film.

  The thickness of the base film is usually 5 to 100 μm, preferably 5 to 50 μm, and particularly preferably 5 to 30 μm. If the thickness is too thick, the stress concentrated on the wrinkles entering the exterior bag will increase when the vacuum insulation material is finished, and the possibility of pinholes will increase. In such a case, sufficient strength as an exterior bag cannot be obtained, and the bag tends to break during processing and use.

The vapor deposition layer in this invention is an aluminum vapor deposition layer .

In the present invention, the vapor deposition layer needs to be a multistage vapor deposition layer composed of at least two layers formed by multistage vapor deposition on a base film.
Hereinafter, in the present specification, when the multi-stage vapor deposition layer is formed by n-stage vapor deposition, the first stage vapor deposition layer, the second stage vapor deposition layer,. -It shall call an nth step vapor deposition layer.

  The total thickness of the multi-stage vapor deposition layer is usually 200 to 1200 mm, preferably 400 to 1000 mm, and particularly preferably 600 to 1000 mm. If the total thickness is too large, cracks tend to occur in the deposited layer itself when an external force is applied, and if it is too thin, the desired water vapor barrier property tends to be difficult to obtain.

  In particular, with regard to the thickness of the first-stage vapor deposition layer, the first-stage vapor deposition layer is formed by directly vapor-depositing the base film, so that the thickness can be controlled relatively easily. The thickness of the film tends to have a great influence on the physical properties of the entire multi-stage vapor-deposited layer. Therefore, the thickness is preferably 200 to 600 mm, particularly preferably 250 to 550 mm, particularly 300 to 500 mm. It is preferable.

  The thickness of each layer after the second-stage vapor deposition layer is preferably 100 to 500 mm, particularly preferably 150 to 450 mm, and further preferably 200 to 400 mm. Furthermore, regarding the total thickness of the second stage vapor deposition layer to the n th stage vapor deposition layer (referred to as additional vapor deposition layer), the ratio of the thickness of the additional vapor deposition layer to the thickness of the first stage vapor deposition layer is 0.2-2. It is preferably 0.5 times, particularly preferably 0.3 to 1.5 times, and further preferably 0.4 to 1 times. If this ratio is too low, effects such as gas barrier properties due to the addition of a vapor deposition layer tend to be difficult to exert. If it is too high, the thickness of the additional vapor deposition layer becomes thick and the weight increases, so that the vapor deposition layer is detached. It tends to be easier.

  The number of times of vapor deposition in such multi-stage vapor deposition is 2 times or more in order to positively attach a new vapor deposition substrate to the non-adhesion portion (sea portion) of the vapor deposition material laminated in the sea island state on the surface of the base film. It is necessary to be, preferably 2 to 4 times, particularly preferably 2 times from the viewpoint of economy. In general, considering that a thickness of at least 100 mm is given by a single vapor deposition operation, if the number of vapor depositions is too large, the total thickness of the vapor deposition layer becomes too thick, and when an external force is applied, the vapor deposition layer itself cracks. It tends to occur easily.

As the vapor deposition method of the present invention, for example, a general vacuum vapor deposition method such as a sputtering method, an ion plating method, a resistance heating vapor deposition method, a high frequency induction heating vapor deposition method, an electron beam heating vapor deposition method, or the like can be used. It is also possible to pre-treat the surface of the base film before performing the vapor deposition on the material film. Examples of such pre-treatment include a method for promoting activation of the base material itself such as corona treatment, and polyethylene. And a method of forming a thin film layer with a coating agent that uses a polyether as a main component and a urethane-based curing agent.

The gas barrier film (B) used in the present invention may be a film having gas barrier properties, and is usually described in JIS K 7126 (isobaric method) under the condition of 23 ° C.-50% RH among such gas barrier films. It is preferable to use a film having an oxygen permeation amount of 1 ml / (m ² · day · atm) or less when measured according to the above method, in particular, 0.1 ml / (m ² · day · atm) or less. It is preferable to use a film. Specifically, a vinyl alcohol film is particularly preferable in terms of obtaining high gas barrier properties.

Such a vinyl alcohol film is formed from a vinyl alcohol resin, and the vinyl alcohol resin may have any vinyl alcohol unit obtained by saponifying a vinyl ester unit. the system resin, Po polyvinyl alcohol resin (hereinafter, sometimes abbreviated as PVA-based resin) can be mentioned. Furthermore, examples of the PVA resin include PVA obtained by homopolymerizing vinyl acetate and saponification thereof, and modified PVA. Examples of such modified PVA include copolymer modified products and post-modified products. it can.
The vinyl alcohol-based film, but may be a known PVA resins or Ranaru film will be briefly described the resin.

The PVA resin will be described.

  Examples of the PVA resin include PVA and modified PVA as described above, and PVA is produced by homopolymerizing vinyl acetate and further saponifying it. The modified PVA is produced by copolymerizing an unsaturated monomer copolymerizable with vinyl acetate and vinyl acetate and then saponifying, and the amount of modification is usually less than 10 mol%.

  Examples of the unsaturated monomer copolymerizable with vinyl acetate include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene, 3-buten-1-ol, and 4-pentene. Derivatives such as hydroxy group-containing α-olefins such as -1-ol and 5-hexen-1-ol and acylated products thereof, acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, undecylenic acid Unsaturated acids such as salts, monoesters or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, amides such as diacetone acrylamide, acrylamide and methacrylamide, ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid Olefin sulfonic acids such as Or salts thereof, alkyl vinyl ethers, dimethylallyl vinyl ketone, N-vinyl pyrrolidone, vinyl chloride, vinyl ethylene carbonate, 2,2-dialkyl-4-vinyl-1,3-dioxolane, glycerol monoallyl ether, 3,4 -Vinyl compounds such as diacetoxy-1-butene, substituted vinyl acetates such as isopropenyl acetate and 1-methoxyvinyl acetate, vinylidene chloride, 1,4-diacetoxy-2-butene, and vinylene carbonate.

  Moreover, as modified PVA, it can also manufacture by post-modifying PVA. Examples of such post-modification methods include a method of converting PVA into acetoacetate ester, acetalization, urethanization, etherification, grafting, phosphoric esterification, and oxyalkylene.

  In the present invention, the polymerization degree of the PVA resin is preferably 1100 or more and the average saponification degree is 90 mol% or more, and the more preferable range of the polymerization degree is 1100 to 4000, and the particularly preferable range is 1200 to 2600. . If the degree of polymerization is too low, the mechanical strength of the resulting film tends to decrease. If the degree of polymerization is too high, the processability during film formation and stretching tends to decrease. A more preferable range of the average saponification degree is 95 to 100 mol%, and a particularly preferable range is 99 to 100 mol%. If the average degree of saponification is too low, the water resistance is lowered, and the change of the gas barrier property due to humidity tends to be remarkable. Therefore, it is preferable to select a relatively high saponification degree.

Moreover, as a viscosity of the 4 weight% aqueous solution of the said PVA-type resin, 2.5-100 mPa * s (20 degreeC) is preferable, Furthermore, 2.5-70 mPa * s (20 degreeC), Especially 2.5- 60 mPa · s (20 ° C.) is preferable. If the viscosity is too low, mechanical properties such as film strength tend to be inferior, and if it is too high, film-forming properties on the film tend to be poor.
The viscosity is measured according to JIS K6726.

  These PVA resins can be used alone or in combination of two or more.

In the present invention, but it is to film formation using the polyvinyl alcohol-based resin, such film forming method may be of known, not particularly limited, for example, poly drum, on a metal surface such as an endless belt A film is formed by a casting molding method in which a vinyl alcohol-based resin solution is cast to form a film, or a melt molding method in which melt extrusion is performed by an extruder.

Such polyvinyl alcohol-based film, in terms especially of the gas barrier property is preferably used as the biaxially oriented film. It is preferred as the stretching ratio in the machine direction (MD direction) of the biaxially stretched film that written is 2.5 to 5 times.

Such stretching process is typically performed that simultaneous biaxial stretching, such as sequential biaxial stretching can be performed according to known methods.

Will be described whether that biaxially oriented PVA-based specific manufacturing method of the fill-time.

  A PVA-based film (PVA-based film before stretching) is formed using the PVA-based resin. Usually, a PVA-based resin concentration is 5 to 70% by weight, preferably as a stock solution for film formation. A composition of 10 to 60% by weight of PVA resin-water is prepared.

  Such PVA-based resin-water compositions include plasticizers of polyhydric alcohols such as ethylene glycol, glycerin, polyethylene glycol, diethylene glycol, and triethylene glycol, phenolic, amine-based, and the like as long as the effects of the present invention are not impaired. Add appropriate additives such as antioxidants, stabilizers such as phosphate esters, colorants, fragrances, extenders, defoamers, release agents, UV absorbers, inorganic powders, surfactants, etc. There is no problem. Moreover, you may mix other water-soluble resins other than PVA-type resin, such as starch, carboxymethylcellulose, methylcellulose, and hydroxymethylcellulose.

  The method for forming the PVA film is not particularly limited, but after the PVA resin-water composition is supplied to an extruder and melt-kneaded, the film is extruded by the T-die method or the inflation method and dried. Is preferred.

  The melt kneading temperature in the extruder in such a method is preferably 55 to 160 ° C. If the temperature is too low, the film skin will be defective, and if it is too high, the foaming phenomenon tends to occur. Moreover, about the drying of the film after film forming, it is preferable to carry out at 70-120 degreeC, and also it is preferable to carry out at 80-100 degreeC.

Respect PVA-based film obtained above, further by performing the biaxial stretching, the biaxially stretched PVA-based film which need use in the present invention.
For such biaxial stretching, the stretching ratio in the machine flow direction (MD direction) is preferably 2.5 to 5 times, and the stretching ratio in the width direction (TD direction) is preferably 2 to 4.5 times, particularly preferably. The MD has a stretching ratio of 3 to 5 times, and the TD direction has a stretching ratio of 2.5 to 4.5 times. If the draw ratio in the MD direction is too low, it is difficult to improve physical properties due to stretching and the heat resistance tends to be impaired. If it is too high, the film tends to tear in the MD direction. Further, if the stretching ratio in the TD direction is too low, it is difficult to obtain physical properties by stretching, and the heat resistance tends to be impaired. If it is too high, breakage during stretching tends to occur frequently when the film is industrially produced. is there.

  In performing such sequential biaxial stretching or simultaneous biaxial stretching, it is preferable to adjust the water content of the PVA-based film to 5 to 30% by weight, particularly 20 to 30% by weight. The moisture content can be adjusted by a method in which the PVA film before drying is subsequently dried, a method in which a PVA film having a moisture content of less than 5% by weight is immersed in water, or is conditioned. Even if the moisture content is too low or too high, there is a tendency that the stretching ratio in the MD direction and the TD direction cannot be increased in the stretching process.

  Furthermore, after performing biaxial stretching, it is preferable to perform heat setting, and the temperature of such heat setting is preferably selected to be lower than the melting point of the PVA-based resin, particularly 140 to 250 ° C. Is preferred. When the heat setting temperature is lower than the melting point by 80 ° C. or more, the dimensional stability tends to be poor and the shrinkage rate tends to be large. The heat setting time is preferably 1 to 30 seconds, and more preferably 5 to 10 seconds.

  In addition, for the purpose of further reducing the heat deformability, it is possible to subject the biaxially stretched PVA-based film to contact with an aqueous solution and to drying as necessary. In contact with the aqueous solution, an aqueous solution of usually 5 to 60 ° C., preferably 10 to 50 ° C. is used, and the contact time with the aqueous solution is appropriately selected according to the temperature of the aqueous solution, but industrially 10 to Preferably it is 60 seconds.

  The contact method with such an aqueous solution is not particularly limited, and examples thereof include immersion in an aqueous solution, spraying of an aqueous solution, application of an aqueous solution, steam treatment, and the like, and these can be used in combination. After contact with the aqueous solution, industrially, it is preferable to remove the adhering water on the surface in a non-contact manner with an air shower or the like, and then to remove the moisture in a contact manner with a nip roll or the like. Further, the type of the dryer is not particularly limited, and examples thereof include a method of directly contacting a metal roll, a ceramic roll or the like for drying, or a method using a non-contact type dryer.

When the obtained biaxially stretched PVA-based film is wound up again after the contact with the aqueous solution and drying, the water content of the film is usually 3% by weight or less, preferably 0.1 to 2% by weight. % Is desired. If the amount of moisture is too large, the films tend to adhere to each other in the film roll, and there is a risk of problems such as damage to the film when unwinding for processing again.
Thus, a biaxially stretched PVA film suitably used in the present invention is obtained.

  The thickness of the gas barrier film (B) used in the present invention is usually 5 to 100 μm, preferably 8 to 50 μm, particularly preferably 8 to 30 μm, from the viewpoint of industrial productivity.

  The gas barrier film (B) alone has sufficient low thermal conductivity, high gas barrier properties and heat resistance, so that it can be used as a gas barrier layer, but also has the purpose of imparting heat radiation comparable to that of an aluminum foil. Thus, it is preferable to provide a paint layer.

In the case of applying a paint layer, any paint can be selected, but from the viewpoint of thermal radiation characteristics, the reflectance of the paint layer is preferably 60% or more, particularly 80% or more, White, white silver, silver and the like are preferably used. The method for forming the paint layer is not particularly limited, but a method of applying a commercially available paint by a printing method such as gravure printing, offset printing or flexographic printing is practical.
The binder of the gas barrier film (B) and the coating layer is not particularly limited, but it is preferable from the viewpoint of adhesion that a urethane-based curing agent is blended in the binder.

  In addition, when the coating layer is applied to the surface of the gas barrier film (B), the surface of the gas barrier film (B) can be pretreated for the purpose of further improving the adhesion with the coating layer. Examples of the pretreatment include a method of promoting activation of the substrate itself such as corona treatment, and a method of forming a thin film layer with a coating agent using polyethylene or polyether as a main ingredient and a urethane-based curing agent.

  The above-mentioned multi-stage vapor deposition base film (A) and gas barrier film (B) are laminated to form a multilayer film. The gas barrier film (B) is preferably laminated on the vapor deposition surface of (A), and the lamination is performed using a known adhesive such as an organic titanium compound, an isocyanate compound, or a polyester compound. (Dry laminating method) is preferably used. However, it is not limited to these methods.

  About the film thickness ratio of the vapor deposition base film (A) and gas barrier film (B) formed by this multistage vapor deposition, the vapor deposition base material formed by multistage vapor deposition with respect to the thickness of a vinyl alcohol-type film (B). The thickness of the film (A) is usually 0.5 to 5 times, preferably 0.5 to 2.5 times.

  Although the thickness of the whole multilayer film in this invention is not specifically limited, Usually, 20-800 micrometers, Especially 50-500 micrometers is preferable.

  The multilayer film in the present invention is a vapor-deposited base film (A) / gas barrier film formed by multi-stage vapor deposition using the vapor-deposited base film (A) and gas barrier film (B) formed by multi-stage vapor deposition. A multilayer film having the layer structure of (B) may be used, but a layer made of a film such as a polyester film, a polyamide film, a polyolefin film, a polyurethane film, or the like, between or between the two layers. You may have other layers, such as an agent layer and a sealing layer.

  Among the above-mentioned other layers, a polyolefin-based layer is formed on the part closer to the outside air than the main barrier layer formed from a multilayer film having a layer structure of vapor deposition base film (A) / gas barrier film (B) formed by multistage vapor deposition. It is preferable to use a film, preferably a polypropylene film, a polyvinyl chloride film, a polyvinylidene chloride film, or a fluorine-based film, in order to reduce water vapor reaching the main barrier layer.

A general-purpose polyolefin film can be used as the polyolefin film.
For example, homopolymers such as polypropylene, polybutene-1, high-density polyethylene, medium-density polyethylene, and low-density polyethylene may be mentioned, as well as ethylene, butene-1, pentene-1, 4-methylpentene-1 having propylene as a main component. , Hexene-1, octene-1, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 1,4-hexadiene, copolymers with styrene, and also grafted with carboxylic acid such as maleic anhydride A modified one, a copolymer of ethylene, propylene, butene-2, isobutylene, butadiene, pentene-1, 4-methylpentene-1, hexene-1, octene-1 and the like mainly containing butene-1; Furthermore, ethylene is the main component that is graft-modified with carboxylic acid such as maleic anhydride. Propylene, butene-1, 4-methylpentene-1, 1-hexene, 1-octene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, styrene, vinyl acetate, methyl acrylate, acrylic acid Examples thereof include copolymers with ethyl, acrylic acid, methyl methacrylate, ethyl methacrylate, methacrylic acid, glycidyl methacrylate, and the like and graft-modified with carboxylic acids such as maleic anhydride. Among these, it is particularly preferable to use polypropylene from the viewpoint of moisture resistance and industrial productivity.

  Further, it is also preferable to perform a stretching treatment and use a uniaxially stretched or biaxially stretched polyolefin film, and in particular, a biaxially stretched polyolefin film is preferably used from the viewpoint of obtaining a higher gas barrier property with a thinner film.

  The thickness of the polyolefin film is usually 5 to 200 μm, and particularly preferably 10 to 100 μm. If the film thickness is too thin, the fillability of the heat insulating material that will be the core material of the resulting vacuum heat insulating structure will be reduced, and if it is too thick, not only will the workability deteriorate, but it will also be economically disadvantageous.

Further, the polyolefin-based film preferably has an initial elastic modulus of 1 to 100 GPa, more preferably 0.5 to 50 GPa, and a water vapor permeability of 10 g / m ² / day or less, further 8 g / m ² / It is preferably not more than day. The initial elastic modulus is 23 ° C. × 60% r.D. measured in accordance with JIS K 7127. h. The water vapor permeability is 23 ° C. × Δ90% r.s measured according to JIS Z 0208. h. The value at.

In the present invention, a heat insulating material is hermetically packaged using the multilayer film thus obtained to form a vacuum heat insulating structure.
In packaging the heat insulating material, the packaging method is not particularly limited. For example, a method of forming an outer bag obtained by processing a multilayer film into a bag shape and placing the heat insulating material therein can be used.

  Thus, when forming an exterior bag with a multilayer film, it is preferable that a multilayer film has a sealing layer in the surface used as the inner side of an exterior bag. Although it does not specifically limit as a sealing layer, A polyolefin-type resin layer is preferable from a viewpoint of sealing strength, and a polypropylene, a high density polyethylene, a low density polyethylene, an ethylene-vinyl acetate copolymer etc. are used suitably especially. As for the sealing layer, a film may be prepared separately from the above resin and further laminated on the inner surface of the outer bag, or may be directly extruded and laminated on the inner surface of the outer bag. When laminating the sealing layer as a film, laminating it as an unstretched film is advantageous in terms of obtaining sealing properties. The thickness of the sealing layer is usually 10 to 100 μm, and particularly preferably 20 to 80 μm.

As a preferred layer structure when sealing and packaging the heat insulating material using the multilayer film of the present invention, from the viewpoint of gas barrier properties and moisture resistance, from the outer layer side (the side opposite to the heat insulating material),
(1): PET film / multi-stage aluminum vapor deposition layer // (adhesive layer) // double-stretched PVA film // (adhesive layer) // polyethylene layer (seal layer))
(2): Biaxially stretched polypropylene film // (adhesive layer) // PET film / multi-stage aluminum vapor deposition layer // (adhesive layer) // bistretched PVA film // (adhesive layer) // polyethylene layer ( Seal layer))
(3): PET film / multi-stage aluminum vapor deposition layer // (adhesive layer) // two-stretched PVA film // polyethylene layer (seal layer))
(4): Biaxially stretched polypropylene film // (adhesive layer) // PET film / multi-stage aluminum vapor deposition layer // (adhesive layer) // bistretched PVA film / polyethylene layer (seal layer)) However, it is not limited to such a layer structure.

  The heat insulating material to be put in the outer bag made of the multilayer film is not particularly limited, but a polymer having open cells inside, or an inorganic or metal fine powder is preferably used, and the outer bag made of the multilayer film is evacuated. However, the shape can be maintained. When the inside of the outer bag made of a multilayer film is evacuated and the opening is sealed and used, the polymer of the heat insulating material has no bubbles or has closed cells, This is not preferable because the heat insulation effect is reduced.

  Specific examples of such a heat insulating material include fine powders such as alumina, silica, pearlite, glass wool, rock wool, diatomaceous earth, calcium silicate molded body, urethane foam having open cells, carbon foam, phenol foam, phenol. Examples include polyurethane foam.

  In addition, the heat insulating material may be mixed with a drying agent such as quick lime or calcium chloride because the moisture content of the gas barrier film (B) used may reduce the degree of vacuum. Is also preferable.

  A vacuum heat insulating structure can be obtained by placing such a heat insulating material in an outer bag made of a multilayer film, depressurizing, and finally sealing and closing the opening of the bag. The degree of vacuum of the vacuum heat insulating structure is not particularly limited, but is preferably 1 Torr or less, more preferably 0.8 Torr or less, and particularly preferably 0.6 Torr or less.

  In the present invention, the shape and size of the vacuum heat insulating structure are not particularly limited, and may be determined according to the purpose. For example, the vacuum heat insulating structure may have a shape including one outer bag made of a multilayer film for one vacuum heat insulating structure, or a plurality of outer bags for one vacuum heat insulating structure. The thing of the shape contained may be sufficient.

In the case of a shape including a plurality of such exterior bags, the seal part that becomes a joint between the exterior bag parts becomes a thin part in the vacuum heat insulation structure, and deformation when the vacuum heat insulation structure is deformed Therefore, the vacuum heat insulating structure can be easily deformed, which is preferable.
Furthermore, even when a hole or the like is generated due to an external factor, and the vacuum property of the vacuum heat insulating structure is lost, the decrease in the heat insulating property is kept to a minimum if the shape includes a plurality of exterior bags. Can be preferable.

  As for the size of such a vacuum heat insulating structure, it is often processed into a rectangular parallelepiped shape having a thickness of 5 to 100 mm and a length and width of 100 to 1000 mm. If the volume of the vacuum insulation structure is unnecessarily large, the area that loses performance increases when defects such as holes occur in the bag of the multilayer film, which may reduce the performance of the final product using the vacuum insulation structure. Therefore, it is preferable to set the size appropriately.

  Thus, according to the present invention, a vacuum heat insulating structure having excellent heat insulating performance, small shrinkage due to heat, and no occurrence of deformation can be obtained. Such vacuum heat insulating structures include household appliances such as cooler boxes and bottle cases, household appliances such as refrigerators, jar pots, rice cookers, housing equipment such as water heaters, bathtubs, unit baths, toilet seats, floor heating, solar roofs, Although it can be effectively used as a heat insulating material for a housing system such as a low-temperature radiation plate and a housing building material such as a heat insulating panel for an outer wall, among them, it can be particularly suitably used as a heat insulating material for a refrigerator.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the examples, “parts” and “%” mean weight basis unless otherwise specified.

<Example 1>
[Production of multi-stage vapor deposition substrate film (A)]
Working vacuum degree 1.3 × 10 ^{−2 in} a roll-to-roll vacuum deposition apparatus in which metallic aluminum is evaporated on one side of a commercially available polyethylene terephthalate film (Teijin Tetron PC: thickness 12 μm) by an electron beam heating method. The metal aluminum layer was vapor-deposited to a thickness of 300 mm under the conditions of Pa, and the first-stage aluminum vapor-deposited PET film once wound up in the vapor deposition apparatus was put again in the same vapor deposition apparatus to form the second metal aluminum layer. Vapor deposition was carried out under conditions of 200 mm, and the resulting film was designated as a two-stage vapor deposited PET film (A).
[Production of gas barrier film (B)]
From a hopper of a twin-screw extruder type kneader (screw L / D = 40) whose jacket temperature is set to 60 to 150 ° C., a PVA (polymerization degree 1700, viscosity of 4 wt% aqueous solution 40 mPa · s, saponification degree 99.7) Mol%, sodium acetate content 0.3%, “GOHSENOL NH-17Q” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) and water are supplied by a metering pump at a PVA / water weight ratio of 40/60, kneaded and discharged. The discharge was performed under the condition of an amount of 500 kg / hr.
This discharged material was immediately pumped to a single screw extruder (screw L / D = 30), kneaded at a temperature of 85-140 ° C., extruded from a T-die onto a 5 ° C. cast roll, and then heated at 90 ° C. with a hot air dryer. The film was dried for 2 seconds to prepare a PVA film (thickness 150 μm) having a water content of 25%. Subsequently, the PVA film was stretched 3.8 times in the MD direction, then stretched 3.8 times in the TD direction with a tenter, and then heat-fixed at 180 ° C. for 8 seconds to obtain a biaxially stretched PVA film (B) (thickness 12 μm). )

[Production of multilayer film]
A polyester / isocyanate two-component polyurethane adhesive (manufactured by Takeda Pharmaceutical Co., Ltd.) is applied to the two-stage aluminum deposition surface side of the obtained two-stage aluminum deposition PET film (A) and one side of the biaxially stretched PVA film (B). After laminating at 70 ° C. using “Takelac A-3210” / “Takenate A-3072” manufactured by Takeda Pharmaceutical Co., Ltd. = 3/1 (weight ratio), the laminate was obtained by aging in an environment of 40 ° C. for 2 days.
Further, on the non-deposition surface of the laminated two-stage aluminum vapor-deposited PET film, a commercially available biaxially stretched polypropylene (“OP U-1 # 20” manufactured by Tosero Co., Ltd.) water vapor permeability = 5.38 g / m ² / da
y: thickness 20 μm) was bonded in the same manner, and heat-melted high-density polyethylene (“Novatech HD LY20” manufactured by Nippon Polyethylene Co., Ltd.) was exposed on the exposed surface side of the biaxially stretched PVA film corresponding to the opposite surface of the laminate. Was laminated with a coating thickness of 40 μm while extruding from a T-die coater at a setting of 315 ° C. to obtain a multilayer film (layer constitution = biaxially oriented polypropylene film // adhesive layer // PET film / one-stage aluminum vapor deposition) Layer / 2-stage aluminum vapor deposition layer // adhesive layer // biaxially stretched PVA film // polyethylene layer (seal layer)).

[Production of vacuum insulation structure]
The resulting multilayer film is formed into a square of 20 cm in length and 20 cm in width, stacked so that the high-density polyethylene layers laminated together can be combined, and the periphery of the three surroundings is sealed with a width of 1 cm and bonded together (Seal temperature 140 ° C.), a piece of glass wool having a thickness of 25 mm (“Magroll RR2425” manufactured by Mag Co.) cut into a length of 17 cm and a width of 17 cm is placed inside the obtained bag-shaped multilayer structure, and this is packed in a vacuum packaging device In the state where the degree of vacuum was 0.01 Torr, the remaining one opening was heat-sealed under the same conditions as above to obtain a vacuum heat insulating structure.

<Example 2>
In Example 1, in the formation of the aluminum vapor deposition layer of the two-stage aluminum vapor-deposited PET film, the first-stage vapor deposition thickness was set to 200 mm, the second vapor-deposition thickness was set to 200 mm, and the third vacuum vapor deposition apparatus was used. A multilayer film was obtained by laminating in the same manner except that a vapor-deposited layer of 200 mm was provided and a total of 600 mm of vapor-deposited layers was provided (layer structure = biaxially stretched polypropylene film // adhesive layer // PET film / first stage Aluminum vapor deposition layer / second stage aluminum vapor deposition layer / third stage aluminum vapor deposition layer // adhesive layer // biaxially stretched PVA film // polyethylene layer (seal layer).
Using the resulting multilayer film, a vacuum heat insulating structure was obtained in the same manner as in Example 1.

<Comparative Example 1>
In Example 1, a multilayer film was obtained in the same manner as in Example 1 except that aluminum deposition was performed only once on the PET film and the thickness was 500 mm (layer constitution = nylon film // adhesive layer / / PET film / first-stage aluminum vapor deposition layer // adhesive layer // biaxially stretched PVA film // polyethylene layer (seal layer)).
Using the resulting multilayer film, a vacuum heat insulating structure was obtained in the same manner as in Example 1.

<Comparative example 2>
In Example 1, the biaxially stretched PVA film was excluded, and instead of a commercially available PET film (Teijin Tetron PC: 12 μm) on the surface of the aluminum vapor deposition layer, a polyester / isocyanate two-component polyurethane adhesive (manufactured by Takeda Pharmaceutical Co., Ltd.) Except for pasting at 70 ° C. using “Takelac A-3210” / “Takenate A-3072” manufactured by Takeda Pharmaceutical Co., Ltd. = 3/1 (weight ratio)) and then aging and laminating in an environment of 40 ° C. for 2 days, A multilayer film was obtained in the same manner as in Example 1 (layer constitution = polyethylene film // adhesive layer // PET film / first-stage aluminum deposited layer / second-stage aluminum deposited layer // adhesive layer // PET film. / Polyethylene layer (seal layer)).
Using the resulting multilayer film, a vacuum heat insulating structure was obtained in the same manner as in Example 1.

  The following evaluation was performed about the multilayer film and vacuum heat insulation structure obtained by the said Example and comparative example. The evaluation results are shown in Tables 1 and 2.

<Oxygen permeability>
The oxygen permeability of the multilayer film was measured using MODERN CONTROLS. Using an oxygen permeability measuring device “MOCONOX-TRAN 2/20 type” manufactured by INK (detection limit value 0.01 ml / (m ² · day · atm)) under the condition of 23 ° C.-50% RH, JIS K 71
It was measured according to the method described in No. 26 (isobaric method). In addition, the oxygen permeability as used in the field of this invention is the permeability (ml / (m < ² > * day * atm)) measured by arbitrary film thicknesses. When the oxygen permeation amount is not more than the detection limit value of the above-described apparatus, it is described as ≦ 0.01.

<Water vapor permeability>
Using the L80-5000 type water vapor permeability meter (detection limit value 0.01 g / m 2 / day) (manufactured by Lyssy), the multilayer film was applied to JIS K7129 (Method A) under the condition of 40 ° C.-Δ90% RH. It measured according to the method of description. The moisture permeability referred to in the present invention is a value (g / m ² / day) measured at an arbitrary film thickness. In addition, when the water vapor transmission rate is not more than the detection limit value of the above-described apparatus, it is described as ≦ 0.01.

<Insulation effect>
For the vacuum heat insulating structures of Examples 1 and 2 and Comparative Examples 1 and 2 obtained above, the thermal conductivity (W / mK) was first measured immediately after creation using HC-074 manufactured by Eiko Seiki Co. After measurement, the sample was left in a high-temperature and high-humidity bath at 40 ° C. × 90% rh for 30 days, and the thermal conductivity after the measurement was measured in the same manner.

As shown in Table 1 above, the multilayer film using the multistage vapor deposition substrate films of Examples 1 and 2 has superior oxygen barrier properties as compared with the multilayer film of Comparative Example 1 in which only one stage of aluminum deposition is performed. It can be seen that the film has a water vapor barrier property, and further, as shown in Table 2, the vacuum heat insulating structure using the multilayer films of Examples 1 and 2 is also excellent in heat insulating performance.
On the other hand, the multilayer film of Comparative Example 1 using a single-stage aluminum vapor-deposited base film and the multilayer film of Comparative Example 2 not using a gas barrier film are inferior in both oxygen barrier properties and water vapor barrier properties, It turns out that the heat insulation performance of the vacuum heat insulation structure using this multilayer film is also insufficient.

The multilayer film used in the present invention has excellent gas barrier properties, particularly water vapor barrier properties under high humidity, and also has excellent heat insulation performance. A vacuum heat insulating structure using such a multilayer film has two stages. Since the heat-insulating material is hermetically packaged in a highly airtight laminate formed by laminating a multi-stage vapor deposition base film having the above aluminum vapor deposition layer and a gas barrier film that is a biaxially stretched polyvinyl alcohol film, it is vacuum-resistant. As well as being maintained for a long period of time, it has excellent gas barrier properties and heat insulation performance even under high humidity, so that it can be used in household appliances such as cooler boxes and bottle cases, household appliances such as refrigerators, jar pots, rice cookers, and water heaters. , Housing equipment such as bathtubs, unit baths and toilet seats, floor heating, solar roofs, housing systems such as low-temperature radiation plates, and housing building materials such as heat insulation panels for outer walls, etc. It can be effectively used as a heat medium but, among these, can be used particularly particularly suitable as thermal insulation for refrigerators.

1 is a diagram of a layer configuration of a multilayer film obtained in Example 1. FIG.

1. 1. Biaxially stretched polypropylene film 2. Adhesive layer PET film4. Aluminum vapor deposition layer (first stage vapor deposition layer)
5. Aluminum vapor deposition layer (second stage vapor deposition layer)
6). 6. Adhesive layer 7. Biaxially stretched PVA film Polyethylene layer (seal layer)

Claims (6)

Have a layer structure of the vapor deposition substrate film having at least two layers of aluminum deposited layer formed by a multistage evaporation (A) / gas barrier film (B), and the gas barrier film (B) is biaxially oriented polyvinyl A vacuum heat insulating structure, wherein a heat insulating material is hermetically packaged by a multilayer film which is an alcohol film . The multilayer film is formed by laminating the gas barrier film (B) on the vapor deposition surface of the vapor deposition base film (A) having at least two aluminum vapor deposition layers formed by multistage vapor deposition. The vacuum heat insulating structure according to 1. The vacuum heat insulation according to claim 1 or 2 , wherein the vapor deposition base film (A) having at least two aluminum vapor deposition layers formed by multi-stage vapor deposition is a vapor deposition polyester film or a vapor deposition polyolefin film. Structure . The total thickness of the deposited layer of the deposition substrate film (A) having at least two layers of aluminum deposited layer formed by a multistage evaporation, according to claim 1 to 3, wherein any one, which is a 200~1200Å Vacuum insulation structure . In the vapor deposition layer of the vapor deposition base film (A) having at least two aluminum vapor deposition layers formed by multi-stage vapor deposition, the second stage relative to the thickness of the first stage vapor deposition layer closest to the base film The ratio of the total thickness of subsequent vapor deposition layers is 0.2 to 2.5 times, The vacuum heat insulation structure in any one of Claims 1-4 characterized by the above-mentioned. The vacuum heat insulating structure according to any one of claims 1 to 5 , wherein the heat insulating material is hermetically packaged with the gas barrier film inside.

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